CoChat
Sign Up
Cited by 18Chronic Myeloid Leukemia TreatmentsRNA Research and SplicingProtein Tyrosine Phosphatases

Discovery of a Novel CIP2A Variant (NOCIVA) with Clinical Relevance in Predicting TKI Resistance in Myeloid Leukemias

Open access
Mäkelä, Eleonora, Pavic, Karolina, Varila, Taru, Salmenniemi, Urpu, Löyttyniemi, Eliisa, Nagelli, Srikar G., Ammunét, Tea, Kähäri, Veli-Matti +6 more·2021·Clinical Cancer Research
DOI 10.1158/1078-0432.ccr-20-3679

Published version of a preprint

Open this paper in CoChat — free accountOpen PDF

Abstract

Purpose: Cancerous inhibitor of protein phosphatase 2A (CIP2A) is an oncoprotein that inhibits the tumor suppressor PP2A-B56α. However, CIP2A mRNA variants remain uncharacterized. Here, we report the discovery of a CIP2A splicing variant, novel CIP2A variant (NOCIVA). Experimental Design: Characterization of CIP2A variants was performed by both 3′ and 5′ rapid amplification of cDNA ends from cancer cells. The function of NOCIVA was assessed by structural and molecular biology approaches. Its clinical relevance was studied in an acute myeloid leukemia (AML) patient cohort and two independent chronic myeloid leukemia (CML) cohorts. Results: NOCIVA contains CIP2A exons 1 to 13 fused to 349 nucleotides from CIP2A intron 13. Intriguingly, the first 39 nucleotides of the NOCIVA-specific sequence are in the coding frame with exon 13 of CIP2A and code for a 13-amino acid peptide tail nonhomologous to any known human protein sequence. Therefore, NOCIVA translates to a unique human protein. NOCIVA retains the capacity to bind to B56α, but, whereas CIP2A is predominantly a cytoplasmic protein, NOCIVA translocates to the nucleus. Indicative of prevalent alternative splicing from CIP2A to NOCIVA in myeloid malignancies, AML and CML patient samples overexpress NOCIVA, but not CIP2A mRNA. In AML, a high NOCIVA/CIP2A mRNA expression ratio is a marker for adverse overall survival. In CML, high NOCIVA expression is associated with inferior event-free survival among imatinib-treated patients, but not among patients treated with dasatinib or nilotinib. Conclusions: We discovered a novel variant of the oncoprotein CIP2A and its clinical relevance in predicting tyrosine kinase inhibitor therapy resistance in myeloid leukemias.

AI snapshot

Written from the paper’s full text.

TL;DR

The paper identifies NOCIVA, an alternatively spliced CIP2A variant encoding a unique 13-amino-acid C-terminal tail, which binds PP2A-B56α and localizes to the nucleus. In AML and CML cohorts, high NOCIVA expression or a high NOCIVA/CIP2A ratio predicts adverse outcomes, with high NOCIVA specifically predicting imatinib resistance in CML but not dasatinib/nilotinib resistance.

Key findings

  • NOCIVA contains CIP2A exons 1–13 fused to 349 nucleotides from intron 13; the first 39 nucleotides are in frame with exon 13 and encode a 13-amino-acid peptide tail (NNKNTQEAFQVTS), yielding a 545-amino-acid CIP2A-shared sequence plus 13 unique amino acids. NOCIVA binds B56α with equal efficiency to CIP2A (P = 0.405), heterodimerizes with CIP2A at lower affinity than CIP2A homodimers (P = 0.017), and is predominantly nuclear whereas CIP2A is cytoplasmic.
  • In patient samples, 77% of AML and 65% of CML samples overexpressed NOCIVA compared with normal bone marrow controls, while 96% of AML and 94% of CML samples expressed lower CIP2A than controls. In normal tissues, absolute NOCIVA expression was below 7% of CIP2A in all tissues.
  • In 80 patients with AML, high NOCIVA mRNA expression predicted shorter overall survival (P = 0.022 by log-rank); in multivariable analysis, NOCIVA was an independent prognostic factor (P = 0.0205; HR, 1.51), alongside age at diagnosis (P = 0.0013; HR, 1.07) and EVI1 (P = 0.0004; HR, 1.27). A high NOCIVA/low CIP2A expression ratio also predicted inferior overall survival (P = 0.042 by log-rank).
  • In CML cohort 1, high NOCIVA expression was associated with shorter event-free survival (P = 0.024), specifically among imatinib-treated patients (P = 0.004) but not second-generation TKI-treated patients (P = 0.429); high NOCIVA also predicted inferior time to complete molecular response (P = 0.039), and none of the high-NOCIVA patients achieved CMR. In CML cohort 2, imatinib-treated patients who progressed had higher diagnostic NOCIVA expression (P = 0.04), and the highest quartile had inferior freedom from progression (P = 0.039), with no association among dasatinib-treated patients (P = 0.863).

Methods

  • Discovery and characterization used 3′ and 5′ RACE from PNT2, MDA-MB-231, and HeLa cells; deep RNA sequencing of 8 AML bone marrow samples; recombinant GST pulldown binding assays; NOCIVA-specific antibodies; immunofluorescence; and quantitative real-time PCR assays for NOCIVA and CIP2A.
  • Clinical validation used an AML cohort of 80 patients (median age 50 years; all received anthracycline and high-dose cytarabine induction), CML cohort 1 of 35 newly diagnosed chronic phase patients (34 analyzed; 20 imatinib, 14 dasatinib or nilotinib), and CML cohort 2 of 159 patients from the SPIRIT2 trial (81 imatinib, 78 dasatinib).
  • Survival analyses used Kaplan-Meier estimates with log-rank tests and Cox proportional hazards models; continuous variables were compared with Kruskal-Wallis, Mann-Whitney, one-sample t, or Student t tests, categorical variables with Fisher exact test, and correlations with Pearson pairwise analysis; two-sided P < 0.05 was significant.

Limitations

  • The paper states that the authors failed to develop siRNA or CRISPR/Cas9 tools selectively suppressing NOCIVA but not CIP2A, and that further studies are needed to validate the clinical diagnostic value of NOCIVA and the mechanistic basis for imatinib resistance.
  • The paper states that differential functional roles of NOCIVA and CIP2A, including the functional importance of the C-terminal CIP2A truncation, remain unresolved and require future study.
  • Evident from the text: CML cohort 1 was small (34 analyzed) and overall survival could not be analyzed because only one death occurred at 60 months; CML cohort 2 included the first 141 biobanked samples plus 18 additional patients whose disease progressed, which may enrich for progression; and the AML prognostic findings come from a single 80-patient cohort without an independent AML validation cohort reported.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1158/1078-0432.ccr-20-3679

Cites

50 of 50 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 32 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    The predicted NOCIVA protein has 545 amino acids shared with CIP2A followed by the NOCIVA-specific peptide NNKNTQEAFQVTS.

    “Therefore, the potential NOCIVA protein consists of 545 amino acids that are shared with CIP2A, followed by the NOCIVA-specific peptide sequence NNKNTQEAFQVTS (Fig. 1B).”
    Quote in the paperSubstantial claim
  • Findingown data

    The first 39 nucleotides of the NOCIVA-specific intronic sequence are in frame with CIP2A exon 13 and encode a 13-amino-acid peptide.

    “Intriguingly, the first 39 nucleotides of the NOCIVA-specific sequence are in the coding frame with exon 13 of CIP2A and code for a 13-amino acid peptide tail nonhomologous to any known human protein sequence.”
    • Also stated in: § Characterization of NOCIVA protein · plain
      “After 39 nucleotides, corresponding to 13 amino acids (red text in Fig. 1B), the C-terminal tail is followed by a classical stop codon TAA.”
    Quote in the paperSubstantial claim
  • Findingown data

    The 13-amino-acid NOCIVA-specific peptide sequence does not match any known human protein sequence in a BLAST homology search.

    “The novel 13-amino acid peptide sequence in NOCIVA did not match any known protein sequence in the human proteome based on a BLAST homology search (ref.33; Supplementary Fig. S4A, BLASTP 2.8.1þ,Database: nonredundant protein sequences).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites ref.33

      Not checked in the free run.

    • Rests on an assumption: The BLAST nonredundant protein database is comprehensive enough to establish that the NOCIVA-specific peptide has no known human homolog.
  • Findingown data

    NOCIVA retains the ability to bind the PP2A B56a subunit.

    “NOCIVA retains the capacity to bind to B56a”
    • Also stated in: § Characterization of NOCIVA protein · plain
      “both proteins coimmunoprecipitated B56a with equal efficiency in vitro (Fig. 3A).”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The in vitro binding, dimerization, and localization results for NOCIVA reflect its behavior in patient leukemia cells.
  • Findingown data

    NOCIVA is a novel CIP2A mRNA splice variant made of CIP2A exons 1 through 13 joined to a 349-nucleotide segment from intron 13.

    “NOCIVA contains CIP2A exons 1 to 13 fused to 349 nucleotides from CIP2A intron 13.”
    • Also stated in: § Identification of a NOCIVA mRNA isoform · plain
      “NOCIVA composed of exons 1 to 13 of CIP2A fused C-terminally to a part of the intron between exons 13 and 14 (Fig. 1A).”
    • Also stated in: § Identification of a NOCIVA mRNA isoform · plain
      “This 349-nucleotide intronic region (Fig. 1A; Supplementary Fig. S2B) is normally located within intron 13 of the CIP2A gene”
    Quote in the paperSubstantial claim
  • May combine two claims. 27
  • Classified as probably not a substantial claim. 19
  • The quote only partly states this claim. 3

  • May combine two claims.

    Findingown data

    NOCIVA can heterodimerize with CIP2A, but with lower affinity than CIP2A homodimers.

    “NOCIVA could also competently heterodimerize with CIP2A 1-560, albeit with lower affinity than that seen with CIP2A 1-560 homodimers (Fig. 3B).”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: The in vitro binding, dimerization, and localization results for NOCIVA reflect its behavior in patient leukemia cells.

  • May combine two claims.

    Findingown data

    The NOCIVA transcript contains a stop codon, a 330-nucleotide 3' untranslated region with a polyadenylation signal AATAAA, and a poly(A) tail, supporting that it is a functional mRNA.

    “As clear evidence that NOCIVA constitutes a functional mRNA transcript, NOCIVA mRNA contains a stop codon followed by a 330-nucleotide 3 0 untranslated region (UTR) with a polyadenylation signal (PAS) AATAAA and a poly(A) tail (Fig. 1B; Supplementary Fig. S2B).”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Findingnone given

    NOCIVA expresses a novel immunogenic peptide sequence.

    “Hence, NOCIVA expresses a novel immunogenic peptide sequence”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    The highest NOCIVA/CIP2A mRNA ratio in normal tissues occurs in leukocytes, kidney, and pancreas.

    “leukocytes, the kidney, and the pancreas had the highest NOCIVA/CIP2A mRNA ratio (Fig. 4B).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    NOCIVA protein localizes predominantly to the nucleus, while CIP2A is mainly cytoplasmic.

    “Strongly indicative of the alternative cellular functions of CIP2A and NOCIVA, the NOCIVA protein was found to be predominantly nuclear, whereas CIP2A mainly resides in the cytoplasm.”
    Quote in the paperNot a substantial claim

  • May combine two claims. The quote only partly states this claim.

    Findingown data

    Deep RNA sequencing of eight AML patient samples detected NOCIVA-specific reads in two samples and verified the novel exon 13-intron 13 junction.

    “Two of eight analyzed samples had detectable expression of reads aligning with the NOCIVA-specific sequence (Fig. 2C; Supplementary Fig. S3C).”
    • Also stated in: § Identification of a NOCIVA mRNA isoform · plain
      “Both IGV analysis and Sashimi plots verified the existence of a novel junction site resulting in a fusion between CIP2A exon 13 and the NOCIVA-specific sequence within intron 13 of the KIAA1524 gene (Fig. 2C; Supplementary Fig. S3D).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    NOCIVA mRNA is expressed at low levels across normal human tissues, with a tissue expression profile comparable to CIP2A.

    “NOCIVA showed overall low levels of expression across normal human tissues (Fig. 4A), but consistent with its regulation from the same promoter region as CIP2A, the expression profile across different tissues, including high expression in testis, was comparable with that of CIP2A (Fig. 4A; Supplementary Fig. S5B).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    NOCIVA is a novel, alternatively spliced CIP2A variant expressed in multiple cancer cell lines.

    “Together, these results identify NOCIVA as a novel, alternatively spliced CIP2A variant that is expressed in multiple cancer cell lines.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingcitation

    hnRNP A1, A2B1, and C were predicted to bind the NOCIVA junction site.

    “A recent study reported expression changes in 13 hnRNPs affecting mRNA processing in AML (39), among which hnRNP A1, A2B1, and C were predicted to bind to the NOCIVA junction site.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingnone given

    NOCIVA is a newly identified CIP2A variant that has clinical relevance.

    “Here, we describe a novel clinically relevant CIP2A variant, NOCIVA.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The NOCIVA junction site contains ESS sequences and predicted binding sites for hnRNPs and other splice factors.

    “At the NOCIVA junction site, ESS sequences, as well as binding sites for hnRNPs and various splice factors were found (Fig. 1C).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    In imatinib-treated CML, high NOCIVA mRNA is associated with worse EFS and FFP and lower CMR rates.

    “In CML, high NOCIVA mRNA expression was associated with inferior EFS and FFP, as well as lower rates of CMR in patients with CML treated with imatinib.”
    Quote in the paperSubstantial claim

  • The quote only partly states this claim.

    Findingown data

    In all normal tissues examined, NOCIVA absolute expression is below 7% of CIP2A expression.

    “Although the absolute expression of NOCIVA was below 7% of CIP2A in all tissues”
    Quote in the paperNot a substantial claim

  • May combine two claims. The quote only partly states this claim.

    Findingown data

    NOCIVA protein localizes abundantly to the nucleus, unlike the predominantly cytoplasmic CIP2A.

    “whereas CIP2A is predominantly a cytoplasmic protein, NOCIVA translocates to the nucleus.”
    • Also stated in: § Characterization of NOCIVA protein · plain
      “Hence, NOCIVA expresses a novel immunogenic peptide sequence, and constitutes a CIP2A variant protein that is abundantly localized to the nucleus.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: The in vitro binding, dimerization, and localization results for NOCIVA reflect its behavior in patient leukemia cells.

  • May combine two claims.

    Findingcitation

    NOCIVA can dimerize and bind B56a.

    “However, similar to CIP2A, NOCIVA retains the capability to dimerize and bind to B56a, indicating that it functions similarly to CIP2A as a PP2A inhibitor protein (1).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    NOCIVA mRNA has a 3' UTR from positions 1,675 to 2,010 and a polyadenylation signal AATAAA at 1,962-1,967.

    “NOCIVA mRNA contains a 3 0 UTR (blue, 1,675-2,010) with a PAS (AATAAA at 1,962-1,967).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    NOCIVA mRNA expression differs between patient-derived normal human epidermal keratinocytes and SCC cells (P=0.0001).

    “NOCIVA mRNA expression in patient-derived normal human epidermal keratinocytes (Ker, NHEK) and SCC cells.mRNA expression levels in Ker 45B cells were defined as value 1. RQ, relative quantification.P ¼ 0.0001 by Student t test.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingnone given

    The work reports discovery of a new human gene and protein that behaves as a clinically relevant PP2A inhibitor in myeloid malignancies.

    “In summary, this work describes the discovery of a novel human gene and protein product with the characteristics of a clinically relevant PP2A inhibitor in myeloid malignancies.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    NOCIVA is a new CIP2A splice variant whose protein product is abundant in the nucleus.

    “NOCIVA is a novel CIP2A splice variant that translates to CIP2A variant protein expressed abundantly in the nucleus.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    NOCIVA mRNA includes an alternative exon from CIP2A intron 13, creating a unique coding sequence.

    “NOCIVA mRNA contains an alternative exon from CIP2A intron 13, and thus forms a unique and previously unknown coding sequence.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    NOCIVA forms heterodimers with CIP2A(1-560), with relative efficiency differing from CIP2A homodimers (P=0.017).

    “The graph shows relative dimerization efficiency of GST-NOCIVA-V5-CIP2A (1-560) heterodimer as compared with GST-CIP2A (1-560)-V5-CIP2A (1-560) homodimer, quantified as a ratio between CIP2A (1-560)-V5 and GST-CIP2A (1-560) from a pulldown sample.Each bar is mean Æ SD from three independent experiments; P ¼ 0.017 by one sample t test.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingnone given

    In CML, NOCIVA is overexpressed at the mRNA level, while CIP2A is overexpressed only at the protein level.

    “Whereas NOCIVA is overexpressed in CML at mRNA level, CIP2A is only overexpressed at protein level.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In the AML cohort, NOCIVA mRNA correlates with PME1, ARPP19, and SET, but not with other studied markers.

    “NOCIVA correlates with PME1 (r ¼ 0.43; P ¼ 0.0002), ARPP19 (r ¼ 0.37; P ¼ 0.0014), and SET (r ¼ 0.30; P ¼ 0.0104), but not with other studied markers.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    CIP2A is overexpressed in many human cancers, and high CIP2A expression correlates with poor patient survival across a broad spectrum of malignancies.

    “CIP2A is overexpressed in a vast variety of human cancers, and high CIP2A expression has been shown to correlate with poor patient survival in a broad spectrum of human malignancies (3)(4)(5)(6).”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [3] Junttila, 2007, CIP2A inhibits PP2A in human malignancies, Cell source

      Not checked in the free run.

    • cites [4] Lucas, 2011, Cancerous inhibitor of PP2A (CIP2A) at diagnosis of chronic myeloid leukemia is a critical determinant of disease progression, Blood source

      Not checked in the free run.

    • cites [5] Khanna, 2016, Clinical significance of cancerous inhibitor of protein phosphatase 2A (CIP2A) in human cancers, Int J Cancer source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductown data

    The study was conducted according to the Declaration of Helsinki, and patients provided informed written consent with ethical review board approval.

    “The study was conducted in accordance with the ethical guidelines of the Declaration of Helsinki.”
    • Also stated in: § AML study cohort · plain
      “All patients gave informed written consent which was signed, and the local Ethical Review Board of Turku University Hospital (Turku, Finland) approved the study protocol.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    hnRNP K, SRSF3, and YB-1 show altered expression in AML and contribute to leukemia progression.

    “In addition, the expression of hnRNP K (40), SRSF3 (SRp20) (41), and YB-1 (42) has been shown to be altered in AML, but also to contribute to leukemia progression.”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [40] Gallardo, 2015, hnRNP K is a haploinsufficient tumor suppressor that regulates proliferation and differentiation programs in hematologic malignancies, Cancer Cell source

      Not checked in the free run.

    • cites [41] Liu, 2012, Aberrant expression of splicing factors in newly diagnosed acute myeloid leukemia, Onkologie source

      Not checked in the free run.

    • cites [42] Liu, 2018, The kinases IKBKE and TBK1 regulate MYC-dependent survival pathways through YB-1 in AML and are targets for therapy, Blood Adv source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Alternative splicing abnormalities play a pivotal role in leukemia pathogenesis.

    “Current evidence suggests a pivotal role of alternative splicing abnormalities in leukemia pathogenesis (12,13).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [12] Yang, 2018, The prognostic significance of global aberrant alternative splicing in patients with myelodysplastic syndrome, Blood Cancer J source

      Not checked in the free run.

    • cites [13] Adamia, 2014, A genome-wide aberrant RNA splicing in patients with acute myeloid leukemia identifies novel potential disease markers and therapeutic targets, Clin Cancer Res source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    A prior study found altered expression of 13 hnRNPs involved in mRNA processing in AML.

    “A recent study reported expression changes in 13 hnRNPs affecting mRNA processing in AML (39), among which hnRNP A1, A2B1, and C were predicted to bind to the NOCIVA junction site.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [39] Alanazi, 2020, Integrated nuclear proteomics and transcriptomics identifies S100A4 as a therapeutic target in acute myeloid leukemia, Leukemia source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    SRSF3 and YB-1 promote exon inclusion during alternative splicing.

    “Interestingly, SRSF3 (43) and YB-1 (44) have also been shown to specifically promote exon inclusion during alternative splicing.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [43] Xiao, 2016, Nuclear m(6)A reader YTHDC1 regulates mRNA splicing, Mol Cell source

      Not checked in the free run.

    • cites [44] Wei, 2012, YB-1 binds to CAUC motifs and stimulates exon inclusion by enhancing the recruitment of U2AF to weak polypyrimidine tracts, Nucleic Acids Res source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    CIP2A is required for malignant cellular growth in vitro and tumor formation in vivo in several cancers, and its overexpression broadly promotes cancer cell drug resistance.

    “Furthermore, CIP2A is required for malignant cellular growth in vitro and for tumor formation in vivo in a number of cancers, and its overexpression broadly promotes cancer cell drug resistance (6)(7)(8)(9)(10)(11).”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [6] Côme, 2009, CIP2A is associated with human breast cancer aggressivity, Clin Cancer Res source

      Not checked in the free run.

    • cites [7] Elgendy, 2019, Combination of hypoglycemia and metformin impairs tumor metabolic plasticity and growth by modulating the PP2A-GSK3beta-MCL-1 axis, Cancer Cell source

      Not checked in the free run.

    • cites [8] Laine, 2013, Senescence sensitivity of breast cancer cells is defined by positive feedback loop between CIP2A and E2F1, Cancer Discov source

      Not checked in the free run.

  • May combine two claims.

    Interpretationown data

    NOCIVA is a novel variant of the oncoprotein CIP2A with clinical relevance for predicting tyrosine kinase inhibitor therapy resistance in myeloid leukemias.

    “We discovered a novel variant of the oncoprotein CIP2A and its clinical relevance in predicting tyrosine kinase inhibitor therapy resistance in myeloid leukemias.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The AML and CML patient cohorts are representative of the broader populations with these diseases.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Among cancers, AML and CML are the only types in which CIP2A mRNA appears lower than in corresponding normal tissue.

    “This is interesting, as AML and CML are the only cancer types in which CIP2A seems to be underexpressed at the mRNA level compared with corresponding normal tissue (Fig. 6I; refs.4,23).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [4] Lucas, 2011, Cancerous inhibitor of PP2A (CIP2A) at diagnosis of chronic myeloid leukemia is a critical determinant of disease progression, Blood source

      Not checked in the free run.

    • cites [23] Barragán, 2015, CIP2A high expression is a poor prognostic factor in normal karyotype acute myeloid leukemia, Haematologica source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    AML prominently features recurrent mutations in spliceosome machinery and genome-wide aberrant splicing events.

    “Particularly in acute myeloid leukemia (AML), a prominent component of the disease is recurrent mutations in spliceosome machinery and genome-wide aberrant splicing events (14)(15)(16)(17).”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [14] de Necochea-Campion, 2016, Aberrant splicing and drug resistance in AML, J Hematol Oncol source

      Not checked in the free run.

    • cites [15] Lindsley, 2015, Acute myeloid leukemia ontogeny is defined by distinct somatic mutations, Blood source

      Not checked in the free run.

    • cites [16] Papaemmanuil, 2016, Genomic classification and prognosis in acute myeloid leukemia, N Engl J Med source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    An expert group recently emphasized the urgent clinical utility of an assay for selecting first-line TKI therapy in CML.

    “The urgent clinical utility of such an assay for CML patient first-line TKI therapy selection was recently highlighted by an expert group (22).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [22] Branford, 2019, Laying the foundation for genomically-based risk assessment in chronic myeloid leukemia, Leukemia source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    CIP2A acts as an oncoprotein by directly binding the tumor suppressor PP2A-B56a.

    “Cancerous inhibitor of protein phosphatase 2A (CIP2A) functions as an oncoprotein by directly binding to the tumor suppressor PP2A-B56a (1,2).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [1] Wang, 2017, Oncoprotein CIP2A is stabilized via interaction with tumor suppressor PP2A/B56, EMBO Rep source

      Not checked in the free run.

    • cites [2] Soofiyani, 2017, The role of CIP2A in cancer: a review and update, Biomed Pharmacother source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    BCR-ABL1/ABL1 mRNA ratios on the international scale predict success of treatment-free remission attempts in de novo chronic phase CML.

    “As an example, BCR-ABL1/ABL1 mRNA ratios on the international scale were shown to predict the success of treatment-free remission attempts for patients with de novo chronic phase CML (46).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [46] Nicolini, 2019, Evaluation of residual disease and TKI duration are critical predictive factors for molecular recurrence after stopping imatinib first-line in chronic phase CML patients, Clin Cancer Res source

      Not checked in the free run.

  • May combine two claims.

    Study design and conductown data

    A NOCIVA-specific antibody detects the expected ~90 kDa recombinant GST-NOCIVA protein but not recombinant CIP2A fragments.

    “NOCIVA-specific antibody detects correct size ($90 kDa) recombinant GST-NOCIVA protein, but not recombinant CIP2A fragments.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationreasoning

    In AML, high NOCIVA expression at diagnosis could indicate a need for first-line therapy intensification.

    “Similarly, in AML, high NOCIVA expression at diagnosis could indicate a need for firstline therapy intensification.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: NOCIVA mRNA levels in patient samples reflect NOCIVA protein levels or functional activity in leukemic cells.

  • Classified as probably not a substantial claim.

    Premisecitation

    Standardized clinical assessment of mRNA expression in CML can be performed with droplet digital PCR and the Cepheid GeneXpert qPCR cartridge system.

    “The technical platforms allowing a standardized clinical assessment of mRNA expression levels for CML samples include droplet digital PCR (ddPCR; ref. 46) and the Cepheid GeneXpert qPCR cartridge system (47).”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [46] Nicolini, 2019, Evaluation of residual disease and TKI duration are critical predictive factors for molecular recurrence after stopping imatinib first-line in chronic phase CML patients, Clin Cancer Res source

      Not checked in the free run.

    • cites [47] Gerrard, 2016, Cepheid xpert monitor platform for the confirmation of BCR-ABL1 IS conversion factors for the molecular monitoring of chronic myeloid leukaemia, Leuk Res source

      Not checked in the free run.

  • May combine two claims.

    Interpretationown data

    In chronic phase CML, high NOCIVA mRNA predicts progression after first-generation TKI imatinib, while high CIP2A protein predicts progression after first- or second-generation TKI.

    “In chronic phase CML, high NOCIVA mRNA level predicts for disease progression after first-generation (1G) TKI (imatinib) treatment, whereas high CIP2A protein level predicts for disease progression after first-generation or second-generation TKI treatment.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: NOCIVA mRNA levels in patient samples reflect NOCIVA protein levels or functional activity in leukemic cells.
    • Rests on an assumption: The AML and CML patient cohorts studied are representative of the broader patient populations.

  • Classified as probably not a substantial claim.

    Premisecitation

    mRNA expression-based diagnostics are now part of clinical CML diagnostics.

    “Although previously debated, mRNA expression-based diagnostics have entered clinical CML diagnostics (45).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [45] Radich, 2018, Chronic myeloid leukemia, version 1.2019, NCCN Clinical Practice Guidelines in Oncology, J Natl Compr Canc Netw source

      Not checked in the free run.

41 of 41

  • The paper relies on this without support.

    The commercial pooled normal bone marrow sample is an appropriate normal comparator for NOCIVA and CIP2A expression in AML and CML patient samples.

    “To estimate the degree of overexpression in the AML and CML cohort 1, the expression of each gene was normalized to the expression level in a commercial normal bone marrow (BM) control sample (pooled from 56 males and females, 636591, lot 1002008, Clontech Laboratories).”

  • The paper relies on this without support.

    The in vitro binding, dimerization, and localization results for NOCIVA reflect its behavior in patient leukemia cells.

    “To address NOCIVA protein functions, recombinant GST-NOCIVA (CIP2A 1-545þ13-amino acid peptide) and GST-CIP2A 1-560 were compared (Supplementary Fig. S4F for Coomassie staining) in terms of two functions critical for CIP2A-mediated PP2A modulation: protein homodimerization and direct binding to the B56a subunit of PP2A (1).”

  • The paper relies on this without support.

    The AML and CML patient cohorts are representative of the broader populations with these diseases.

    “Basic molecular and clinical characteristics for the 80 patients with AML are listed in Supplementary Table S2.”

  • The paper relies on this without support.

    The BLAST nonredundant protein database is comprehensive enough to establish that the NOCIVA-specific peptide has no known human homolog.

    “The novel 13-amino acid peptide sequence in NOCIVA did not match any known protein sequence in the human proteome based on a BLAST homology search”

  • The paper relies on this without support.

    NOCIVA mRNA levels in patient samples reflect NOCIVA protein levels or functional activity in leukemic cells.

    “Our data firmly indicate that high NOCIVA mRNA expression is associated with poor clinical outcomes in both AML and CML.”
    “the determination of NOCIVA mRNA levels from patients with de novo chronic phase CML by ddPCR assay or the Cepheid qPCR cartridge system could provide significant support for clinicians in recognizing patients in need of first-line second-generation TKI therapy.”

  • The paper relies on this without support.

    The NOCIVA/CIP2A mRNA ratio is a valid proxy for the functional balance between NOCIVA and CIP2A in leukemic cells.

    “the detection of NOCIVA/CIP2A ratio at the CML diagnostic phase might help in treatment decision-making between imatinib and second-generation TKIs.”

  • The paper relies on this without support.

    The AML and CML patient cohorts studied are representative of the broader patient populations.

    “On the basis of our nearly identical results from two independent clinical CML cohorts, and independence of NOCIVA from other candidate markers”
7 of 7

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • It is likely that results of this study are relevant also for understanding the mechanism by which NOCIVA promotes myeloid cancer therapy resistance.

    “Therefore, it is likely that results of this study are relevant also for the understanding of the mechanism by which NOCIVA promotes myeloid cancer therapy resistance57.”

    From Structural mechanism for inhibition of PP2A-B56α and oncogenicity by CIP2A (2023) · cites this paper as [57]

    The Discussion (page unavailable) cautiously proposes that NOCIVA contributes to chemotherapy resistance in AML, and the CML results associate high NOCIVA expression with poorer outcomes on imatinib. The paper says the mechanism of resistance requires further study, so it does not establish that NOCIVA promotes therapy resistance across myeloid cancers or explain how it does so. (LLM, conf=0.86)

    Experimental — accuracy not yet measured

  • The recently identified CIP2A variant NOCIVA contains all structural features identified here as critical for CIP2A-B56α interaction.

    “the recently identified CIP2A variant NOCIVA (NOvel CIP2A VAriant), that consists of the N-terminal CIP2A amino acids 1-545 fused to a unique C-terminal tail57, contains all structural features identified here critical for CIP2A-B56α interaction.”

    From Structural mechanism for inhibition of PP2A-B56α and oncogenicity by CIP2A (2023) · cites this paper as [57]

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • CIP2A and NOCIVA survival associations are called opposite despite having the same direction

    Minor

    The paper says high NOCIVA predicts shorter survival and low CIP2A predicts longer survival. Those statements both associate higher expression with shorter survival, contrary to the later description of their roles as opposite.

1 of 1

Cites

Flagged first, then by citations

Cited by

Sorted by citations

Related

Authors
Mäkelä, E., Pavic, K., Varila, T., Salmenniemi, U., Löyttyniemi, E., Nagelli, S. G., Ammunét, T., Kähäri, V.-M., Clark, R. E., Elo, L. L., Bachanaboyina, V. K., Lucas, C. M., Itälä-Remes, M., & Westermarck, J.
Affiliations
  • Åbo Akademi University (FI)
  • Helsinki University Hospital (FI)
  • University of Turku (FI)
  • University of Liverpool (GB)
  • University of Chester (GB)
  • 10Department of Hematology, Turku University Hospital, Turku, Finland.
Corresponding author
Westermarck, Jukka
ORCID
Venue
Clinical Cancer Research
Publisher
American Association for Cancer Research (AACR)
Published
2021-03-05
Volume
27
Issue
10
Pages
2848-2860
ISSN
  • 1078-0432 (ISSN-L)
  • 1557-3265
DOI
10.1158/1078-0432.ccr-20-3679
OpenAlex
W3133817337
Semantic Scholar
1052725dc6d0550ab86eeedc7118e0fe0eb6ce4c
Cited by
18
References
50
Citations by year
2026: 2 · 2024: 3 · 2023: 4 · 2022: 3 · 2021: 6
FWCI
2.93
Type
journal article
Language
en
Open access
Locations
  • Clinical Cancer Research (publishedVersion)
  • bioRxiv (Cold Spring Harbor Laboratory) (acceptedVersion, cc-by-nc-nd)
  • PubMed (publishedVersion)
  • ChesterRep (University of Chester) (submittedVersion, public-domain)
Funders
  • Sigrid Juselius Foundation
  • Turku Doctoral Program of Molecular Medicine
  • Turku University Hospital ERVA (13283, 13336)
  • Päivikki and Sakari Sohlbergin Foundation
  • Cancer Foundation Väre
  • Finnish Cultural Foundation
Topics
  • Health Sciences › Medicine › Hematology › Chronic Myeloid Leukemia Treatments
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › RNA Research and Splicing
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Protein Tyrosine Phosphatases
Keywords
CIP2A, alternative splicing, oncoprotein, acute myeloid leukemia, chronic myeloid leukemia, tyrosine kinase inhibitor resistance, imatinib, dasatinib, nilotinib, nuclear translocation, prognostic factors, overall survival, event-free survival
MeSH terms
Antineoplastic Combined Chemotherapy Protocols, Autoantigens, Base Sequence, Humans, Membrane Proteins, Models, Molecular, Prognosis, Protein Conformation, Structure-Activity Relationship, Biomarkers, Tumor, Leukemia, Myelogenous, Chronic, BCR-ABL Positive, Leukemia, Myeloid, Acute, Gene Expression Regulation, Leukemic, Treatment Outcome, Alternative Splicing, Drug Resistance, Neoplasm, Protein Kinase Inhibitors, Intracellular Signaling Peptides and Proteins, RNA Isoforms

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-07.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-07.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review